AND WINDTUNNELS AERODYNAMICS IS THE STUDY OF THE FORCES EXERTED BY AIR OR OTHER GASES IN MOTION DEFINITION WHY SHOULD WE CARE ABOUT AERODYNAMICS BECAUSE IT SIGNIFICANTLY AFFECTS THE PERFORMANCE amp SAFETY OF MANY OF THE THINGS WE USE AND THINGS WE DO ID: 161342
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Slide1
AERODYNAMICS
AND
WINDTUNNELSSlide2
AERODYNAMICS:
IS THE STUDY OF THE FORCES EXERTED BY AIR OR OTHER GASES IN MOTION
DEFINITIONSlide3
WHY SHOULD WE CARE ABOUT AERODYNAMICS?
BECAUSE IT SIGNIFICANTLY AFFECTS THE PERFORMANCE & SAFETY OF MANY OF THE THINGS WE USE AND THINGS WE DO:AIRCRAFT SPACECRAFTAUTOMOBILES AND TRUCKSENGINES (Gas turbines, reciprocating engines, etc.)AIR HANDLING SYSTEMS (fans, blowers, air conditioners, etc.)BUILDINGSWIND TURBINESSPORTS (Ski jumping,
speed skating,
bicycle racing, windsurfing, yacht racing, etc.)
DESIGN APPLICATIONSSlide4
AERO DESIGN PROCESS
THE SCIENTIFIC METHOD:
FOR THEORY TO BECOME LAW IT MUST BE TESTABLE(otherwise it’s philosophy)
THE
WIND TUNNEL
IS
THE
PRIMARY
TEST VEHICLE FOR AERODYNAMIC DESIGNSlide5
UNDERSTANDING AERODYNAMICS
CONSERVATION OF ENERGY NEWTON’S THIRD LAW OF MOTIONPOTENTIAL & KINETIC ENERGYCONTINUITY EQUATION
GOVERNING LAWS OF PHYSICSSlide6
THE LAW OF CONSERVATION OF ENERGYenergy can neither be created nor destroyed, but only changed from one form into another or transferred from one object to anotherthe total amount of energy in a closed system remains constant
ENERGYSlide7
NEWTONS THIRD LAW
FOR EVERY ACTION THERE IS AN (OPPOSED) EQUAL AND OPPOSITE REACTION
LAWS OF MOTIONSlide8
POTENTIAL ENERGY
PE = mass x g x height = weight x heightKINETIC ENERGY KE = ½ mass x velocity2
=
weight x velocity2
2g
ENERGY TRANSFORMATIONSlide9
THE
FORCES EXERTED BY AIR ARE MANIFEST IN PRESSUREDEFINITIONSlide10
FLOW THROUGH A CONSTRAINED REGION
Continuity Equation W1 = W2 =
W
n flow = density x area x velocity
W = d x A x V
CONTINUITY EQUATION
1
2
nSlide11
STATIC PRESSURE
THE CONCEPT OF PRESSURE
V = 0
OBSERVER MOVING WITH THE AIRSlide12
DYNAMIC (TOTAL) PRESSURE
Pressure due to velocity of air relative to the velocity of the objectTHE CONCEPT OF PRESSURE
OBSERVER MOVING WITH THE OBJECTSlide13
RELATIONSHIP BETWEEN STATIC AND TOTAL PRESSURE
THE CONCEPT OF PRESSURETotal Temp ≈ Static Temp x (1 + c x V2)
Total Press ≈ Static Press x (1 + c x V
2)3.5 Total Press ≈ Static Press x (Total/Static Temp)3.5Slide14
AERODYNAMICS OF WINGS
DEFINITIONSlide15
VELOCITY IS GOVERNED BY THE CONTINUITY EQUATION
Density (d) varies with T & PT & P remain constant unless heat and/or work is added or removed (conservation of energy), thus d = constant
Therefore: W
= constant = d
x A x
V = constant x A x V
Thus V varies only with A (V = constant/A)
VELOCITY
IN A CONSTRAINED SPACESlide16
FLOW OVER A WING
AERODYNAMICS OF WINGSSlide17
PRESSURE DISTRIBUTION AROUND A WING
AERODYNAMICS OF WINGSSlide18
C
AERODYNAMICS OF WINGSSlide19
ANGLE OF ATTACK
AERODYNAMICS OF WINGS
As the angle of
attack increases lift increases but so does dragAt some point the air cannot follow the wing surface and separates. This causes the wing to rapidly lose lift, creating stallSlide20
AERODYNAMIC FORCES ON A WING
AERODYNAMICS OF WINGSSlide21
AERODYNAMIC & PHYSICAL LOADS
ON AN AIRCRAFTAERODYNAMIC LOADSSlide22
LIFT AND DRAG
AERODYNAMICS OF WINGSSlide23
WINDTUNNELS ARE USED TO:
DEVELOP EMPIRICAL DESIGN DATA (eg Lift/Drag polars)INVESTIGATE AERODYNAMIC PHENOMENA (eg flutter)DEVELOP AND VERIFY DESIGNS
WIND TUNNELSSlide24
WRIGHT BROTHERS
WIND TUNNEL WINDTUNNELS
Critical to the Wright Brothers’ success
was their wind tunnel
.
When
they tested their
previous
design that failed expectations they discovered that its lift was 1/3 of design
predictions Slide25
WRIGHT BROTHERS WIND TUNNEL
WINDTUNNELSSlide26
LARGE SCALE WIND TUNNELS
WINDTUNNELSSlide27
OPTIONS
WINDTUNNELS
CLOSED LOOP:
Facilitates changes in altitude (pressure).Reduces energy consumption.OPEN LOOP:Required for engine testing and testing with inlet additives (eg water, contamination, etc.
Ambient
Inlet air heaters & coolers
Exhaust pumps to vary altitude and flight speed.
BLOW DOWN :
Open configuration
Closed configurationSlide28
BLOW DOWN WIND TUNNELS
WINDTUNNELSSlide29
SCHLIEREN , SHADOW GRAPHS, & LDV
USE AIR DENSITY FOR VISUALIZATIONVISUALIZING FLOW FIELDSSlide30
VERTICAL WIND TUNNELS
WINDTUNNELSNASA LEWIS (GLENN) 5 FT VERTICAL WIND TUNNEL - 1917Slide31
NON - AIRCRAFT APPLICATIONS
WINDTUNNELSSlide32
AERODYNAMIC DRAG MEASUREMENT
ON BUILDINGS USING SCALE MODELSWINDTUNNELSSlide33
WIND LOADS ON STRUCTURES
HURRICANES & TORNADOSSlide34
0
HURRICANES AND TORNADOES
EFFECT OF
HIGHWIND SPEED ON HOUSE ROOF LOADSSlide35
AERODYNAMICS OF VEHICLES
OBJECTIVE: REDUCE DRAG FOR REDUCED FUEL CONSUMPTION AND INCREASED SPEED.AUTOMOBILES, RACE CARS, MOTORCYCLES & TRUCKS
WINDTUNNELSSlide36
AUTOMOTIVE APPLICATIONS
GM WIND TUNNEL
MERCEDES BENZ ENVIRONMENTAL TESTING
NASA LANGLEY FULL SCALE TESTINGSlide37
SMOKE STREAMS
FLOW VISUALIZATION
Smoke streams clearly show flow separation and turbulence – which means higher drag and higher fuel consumptionSlide38
HOW TO PREVENT A
CAR FROM BECOMING AN AIRPLANEFLOW VISUALIZATION
INVERTED WING
SPOILERSlide39
WOOL TUFTS
FLOW VISUALIZATIONSlide40
SKI JUMPING DOWNHILL RACING SPEED SKATING
SKY
DIVING BICYCLE RACING
GOLF
AERODYNAMICS IN SPORTSSlide41
SKI JUMPING
WINDTUNNELS
V STYLE
CLASSIC STYLESlide42
SKY DIVING
WINDTUNNELSMODERN VERTICAL WIND TUNNELS – FOR FUN AND GAMESSlide43
RACING APPLICATIONS
WINDTUNNELSSlide44
WHY DIMPLED GOLFBALLS?
AERODYNAMICS OF GOLF
In the early days of golf when the balls were smooth some golfers noticed that their old beat up golf balls drove further than new golf balls – hence the design of dimpled ball covers.Slide45
AERODYNAMICS OF SPEED SKATING
Under Armour and Lockheed
Martin designed gear for the 2014 Winter Olympics Slide46
THE LEADER FIGHTS THE HIGHEST DRAG
AERODYNAMICS OF DRAFTING
PEDALING A BICYCLE AT 152 MPHSlide47
EVERYONE
IN ONE WAY OR ANOTHER IS AFFECTED BY AERODYNAMICS (BUT MOST OF US DO NOT REALIZE IT)
THE
PHENOMENAE OF AERODYNAMICS
AND THE
ATTENDANT
LAWS
OF
PHYSICS
CAN BE DEMONSTRATED WITH A SIMPLE WIND
TUNNEL
ITS ADVANTAGE
IS THAT IT
PROVIDES AN INTERESTING “SEE
AND
TOUCH” APPROACH WITH CONSIDERABLE OPTIONS FOR STUDENTS TO DEVELOP AN UNDERSTANDING OF BASIC SCIENCE
AERODYNAMICSSlide48
Dennis
Barbeau dennisb@innsolinc.com
AERODYNAMICS